Inkjet printers produce images by jetting or ejecting droplets of liquid ink from an inkjet printhead onto a recording substrate (e.g., paper). The printhead typically has a front face with a nozzle opening defined therein, through which liquid ink is ejected as droplets onto the recording substrate.
The front face of an inkjet printhead can become contaminated by wetting or drooling of ink. Such contamination can cause or contribute to partial or complete blocking of the nozzle opening within the front face of the inkjet printhead. This blocking can prevent ink droplets from being ejected from the inkjet printhead, cause under- or over-sized ink droplets to be ejected from the inkjet printhead, alter the intended trajectory of ejected ink droplets onto the recording substrate, and the like, all of which degrade the print quality of inkjet printers.
The front face of an inkjet printhead is typically coated with a material such as polytetrafluoroethylene (PTFE) (e.g., Teflon®) or perfluoroalkoxy (PFA), to protect it. Current printheads like Maverick have good initial performance with Xerox solid ink. However over operational lifetime, the performance degrades and ink does not readily slide over printhead front face coatings at typical ink-ejecting temperatures. Rather, the ink tends to adhere and flow along the printhead front face coating, leaving a residual ink film which can partially or completely block the nozzle opening within the front face of the inkjet printhead. This problem is more severe with UV gel ink, with printhead failure due to drooling happening at initial stage itself. FIG. 1 is a photograph of the front face of an inkjet printhead after a printing run showing wetting and contamination of a UV-curable ink over most of the area of the front face surrounding nozzle openings. Hence oleophobic low adhesion coatings which prevent drooling failure are important to improve robustness and reliability, and enabling new market penetration for future UV gel ink.
Contamination of an inkjet printhead front face can be minimized somewhat by adopting purging and/or wiping procedures. However, these procedures can undesirably consume time and/or use excessive amounts of ink, thereby decreasing the useful life of the inkjet printhead. Contamination of an inkjet printhead front face can also be minimized somewhat by providing an oleophobic low adhesion printhead front face coating that does not wet significantly with ink ejected from nozzle openings of the printhead. When heated to temperatures typically encountered during printhead fabrication processes, however, the surface property characteristics of known oleophobic low adhesion printhead front face coatings degrade to the point that they cannot be relied upon to minimize contamination of the inkjet printhead front face.